It seems that mothy is going around it being the Venom Sword and yes it is the only vessel we know of that can change faces but what if it's not the Venom Sword and the Lust demon has a new vessel or we see some other vessel using Lust's powers. Probably neither are likely but just to be safe I think it should be kept vague as vessel of sin with a link to Sin of Lust. 

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